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R. D. DUNCAN. JR

THREE-PHASE WIRED RADIO RECEIVING CIRCUITS Filed June 5, 1925 .2 sheets-sheet 1 POW GENERA TING POLY on THREE PHASE SOURCE 3051 1739. -Dzzzzrrzxg, cl}:

July 13 1926 v 592,085

I R. D. DUNCAN. JR 4 THREE-PHASE WIRED RADIO n'acsivruefbnidbns I Filed June 5. 1925 2 Shoots-Shoot 2 9 2? =5, ri i Patented July 13, 1926.

UNITED STATES PATENT OFFICE,

ROBERT D. DUNCAN, JR., OF EAST ORANGE, NEIV JERSEY, ASSIGNOR TO WIRED RADIO INC, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

THREE-PHASE WIRED RADIO RECEIVING CIRCUITS.

Application filed June 5, 1925.

My invention relates broadly to carrier wave signaling systems and more particularly to a receiving system for carrier wave line wire operation.

One of the objects of my invention is to provide a circuit arrangement for wired radio receiving systems whereby stray electromagnetic fields or radiation from the line wires over which the high frequency currents are conveyed are substantially negligible thereby eliminating the inherent disadvantages which exist where wired radio signals are thrown open to reception over space radio systems.

Another object of my invention is to provide a circuit arrangement for wired radio receiving systems whereby a plurality of receiving apparatus connecting with the different phases of a polyphase transmission line receive substantially equal amounts of high frequency energy, by virtue of polyphase high frequency transmission and of phase reversing circuits at the receivers.

Still another object of my lnvention is to provide a wired radio receiving system where received currents at a plurality of receiving stations connected along a carrier wave line wire distribution system may be effectively impressed upon translating circuits with relatively large signal intensity by virtue of polyphase transmission.

A still further object of my invention is to provide a receiving circuit arrangement for wired radio systems where the effective energy impressed upon the translating circuit may be considerably augmented by transmitting and receiving three phase carrier wave energy.

My invention contemplates the arrangement of inductances in coupled relation at areceiving station for so reversing the phase of polyphase signaling currents that the several phases are vectorially added to effectively operate the translating device at the wired radio receiver.

In high frequency carrier current communication and broadcasting systems in which the high frequency current is superimposed on electric lighting and power lines, it has been determined that, when the latter form a part of athree phase transmission system, which is the case in practically all of the modern power systems, the generation Serial No. 35,212.

lines, and the practical complete elimination of stray electromagnetic fields or radiation from the lines. The reason for the latter is that the currents in the three phases differ in phase by 120 and in accordance with fundamental electrical theory at any instant their sum is zero or their combined effect upon an external receiver is nil.

In my co-pending applications Serial No. 1,374, filed January 9, 1925., now Patent 1,578,881, issued March 30, 1926, Serial No. 61,019, filed October 7, 1925 and Serial No. 65,125, filed October 27,1925,I have shown a new and novel method for generating high frequency current at polyphase and in particular three phase. In Letters Patent 1,560,505, dated November 3, 1925, I have illustrated one of the applications of polyphase high frequency signaling systems us ing a polyphase high frequency current source similar to that which may be employed in my present system. In long distance high voltage power transmission three phase carrier current operation is especial- 1y beneficial. It is also possible by proper and suitable arrangement of receiving apparatus to derive additional benefits from three phase high frequency operation.

My invention will be more clearly understood by reference to the accompanying drawings, in which Figure 1 is a diagrammatic view showing the arrangement of a wired radio receiving set operating in con junction with a three phase power distribution line upon which three phase carrier wave signaling current is impressed; Figs. 2 and 3 are vector diagrams showing the characteristics of the signaling currents in the three phase carrier wave system and in the wired radio receiving circuit which I provide for connection to the three phase transmission line; Fig. 4; shows another method of operating a wired radio receiver in connection with a three phase carrier wave system; Fig. 5 is a vector diagram showing the characteristic of the signaling currents in the circuit diagram of Fig. 4;

and Fig. 6 shows one of the methods by which the wired radio receiver may be coupled to the transmission line for collecting polyphase signaling energy from the line.

Referring to the drawings in detail reference character 1 in Fig. 1, represents a tion connected with the transmission line.

Connected to the three lines 2, 3 and 4, through coupling condensers 6, 7, and, 8, is a three phase high frequency generating source 9, which supplies modulated high frequency current to the lines. Suitable means are provided in association with the high frequency generating source 9 for effecting modulation by Voice or for forming telegraphic signals. Connected to the lines through condensers 10, 11 and 12 at any desired points along the line adjacent the receiving end are inductance coils 13, 14 and 15 which are shown to be interconnected in star or Y. Inductively coupled to two of these coils, for example, 13 and 14 is a series circuit made up of inductance coils 16 and 17 and capacity 18. The capacity 18 may or not be variable. Inductances 16 and 17 are substantially identical in construction and have approximately the same number of turns wound in the same direction. Coils 16 and 17 are connected in reverse manner however as illustrated. The receiving circuit contains a suitable translating device for observing the received signals. A cryst-al detector 19 is shown connected in the receiving circuit with telephone receivers 21 shunted by condenser 20.

In Fig. 4, I have shown the circuits 10, 11, 12. 13, 14 and 15 the same as in Fig. 1. In this arrangement the inductance coil 17 is coupled to coil 14 in the same sense as coil 16 is coupled to coil 13. Inductance coil 22 with its connections reversed in a manner similar to the arrangement of coil 17 in Fig. 1 is coupled to inductance 15. Coils 16, 17 and 22, and capacity 18 form a series circuit. Across capacity 18 may be connected an electron tube amplification circuit or detector represented in its entirety by numeral 23.

The operation of the system, as illustrated in Fig. 1 may be explained with the assist ance of the vector diagrams of Figs. 2 and 3. The three phase high frequency signaling currents, modulated or unmodulated, established in the lines 2, 3 and 4 by generator 9, cause to flow in the three phase coils 13, 14 and 15 three equal currents 1,, I I differing in phase by 120 degrees as indicated in Fig. 2. The magnetic field established by coils 13 and 14 induce voltages in coils 16 and 17 which give rise to currents I and ()P,. The current ()I is displaced 180 degrees from I by virtue of the reversed connection of coil 17 and with respect to coil 16. The resultant current in circuit 16, 17 and 18 which may or may not be tuned to resonance, is the vector sum of I" and (-)I and is equal to /8, or 1.732 times either P or ()I due to the fact that the phase angle between these currents has been changed from 120 to 60. The value of the effective current is therefore indicated at I which is the vector sum of I and I This efiective current I actuates the translating circuit containing detector 19 and telephone 21. I

With reference to the vector diagram in Fig. 5 the vector currents which tend to flow in the receiving circuit of Fig. 4 have been illustrated. The resultant of vector currents I I which tends to flow in circuits 16, 17 18 and 22, under the action of voltages induced in coils 16 and 17, is a vector which is equal to and coincides with vector marked -)I Due to the reverse coupling between coils 15 and 22, the current I caused to flow by voltage induced in coil. 22 is reversed 180 degress in phase from its normal position, its normal position being shown in dotted lines and is indicated by )P,. The final resultant current flow I in the circuit is the vector sum of these resultants and is equal to 2.1 221 since the vector resultant of I and 1 which are equal and is itself equal to (-)I add directly. It is to be noted that with the connection to coil 22 reversed from that shown or with the coupling reversed the resultant current'in circuit 16, 17, 18 and 22 would be zero, since the three component currents I I I which tend to flow are all equal in amplitude, differ in phase by 120 degrees, and hence add up to zero.

As shown more clearly in Fig. 6 the high frequency carriercurrent may be collected from the lines23, 24 and 25 by virtue of the electrostatic coupling existent between coupling wires 26, 27 and 28 which are suspended along the line wire system but substantially insulated therefrom throughout their length. Each of the coupling wires is insulated at each end as indicated at 26 and 26" and the coupling wire closely parallels the wire system throughout its length.

By methods shown in Figs. 1 and 4, the use of three phase high frequency signaling energy for carrier operation over high voltage power lines is made possible with its accompanying advantages of substantially non-radiation and increased signal strength which polyphase reception makes possible as compared with single phase reception. It will be observed that the effective received current which actuates the translating circuit is represented by the vector I in Figs. 3'and 5 and that the value thereof is substantially greater. than the current value which could be effectively secured by merely coupling the receiving circuit to the line in a single phase system.

It will be noted that a reversed connection is shown at inductanceli", Fig. 1, and in ductance 22, Fig. 4. It is obvious that an equivalent effect can be obtained with inductances 17 and 22, symmetrically connected with the remaining inductances of the circuitcontaining them, but with their direction of winding reversed from that of the remaining inductances. This change obviously falls within the scope of this inven tion, since the essential requirement is that of obtaining substantially a complete phase reversal of one of the component currents established in the circuit containing inductances 16 and 17 of Fig. 1, and 16, 17 and 22 of Fig. i, and this may be accomplished either one of the two ways described.

With regard to the theory of the circuits shown, it should be noted that the reversed connection of coils 17 and 22 is to obtain a complete phase reversal of the component of current induced in these coils. This phase reversal may be accomplished either by reversal of connections as shown, or by symmetrical connection of the coils but reversed in the direction of winding of the same as hereinbefore pointed out. By virtue of this reversal theresultant vector current of circuit 16, 1'7 and 18 of Fig. 1 is substantially equal to /g times either of the individual component currents induced through coupling between coils 1316, and 1 l17, said component currents of course being equal undersynnnetrical conditions of coil construction and coupling. In Figs. 4; and 5, this phase reversal yields a resultant vector current of twice the individual component current-s, which latter will be equal under symmetrical coil conditions. It is assumed, of course, that the coupling between 18-16, 1 l17 and 15 component currents. Comparing conditions of Figs. stand 5 with Figs. 1 and 3, it is noted that the resulting currents in the secondary circuits under the same conditions of tuning at condenser 18, are in the ratio 2 r w/g 1.150,

certain particular embodiments, I desire that it be understood that modifications may be made and that no limitations upon the 1n- 22 is always adjusted to yield maximum 1 vention are intended other than are imposed by the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is as fol-" from said line circuit and a translating circuit connected with said last mentioned means arranged to effectively utilize the received energy at an effective amplitude equal to the vector sum of the energy in the separate phases.

2. A wired radio communication system comprisingin combination a line circuit, means for impressing three phase signaling energy on said line circuit, means for collecting the three phase energy from said line circuit and a translating circuit connected with said last mentioned means, said translating circuit having means for reversing the phase of one of the phases of said signaling energy for vectorially adding the currents in the several phases for effectively actuating apparatus in said translating circuit.

3. A wired radio communication system comprising in combination a line circuit, means for impressing three phase signaling energy on said line circuit, means for collecting the three phase energy from said line circuit and a translating circuit connected with said last mentioned means, said translating circuit including oppositely connected inductance coils and means connected with said inductance coils for Vectorially adding the effects of the currents in all of said phases.

A wired radio communication system comprising in combination a line circuit, means for impressing three phase signaling energy on said line circuit, means for collecting the three phase energy from said line circuit, a plurality of inductances connected with said last mentioned means, a plurality of separate inductances coupled to said first mentioned inductances, a receiver circuit connected with said last mentioned inductances, means in said receiver circuit for observing the signaling energy, said second mentioned inductances being arranged to make efl'ective upon said last mentioned means signaling energy of an amplitude greater than the amplitude of the energy in the separate phases.

5. A wired radio communication system comprising in combination a line circuit means for impressing three phase signaling energy on said line circuit, means for collecting the three phase energy from said line circuit, a plurality of: inductances connected to each phase of said line circuit, a plurality of inductances coupled with each of said first mentioned inductances, said second mentioned inductances being connected in reverse order for vectorially adding the currents in said phases and means connected with said last mentioned inductances for observing the received signaling energy.

6. A wired radio communication system comprising in combination a line circuit, means for impressing three phase signaling energy on said line circuit, means for collecting the three phase energy from said line circuit, a plurality of inductances connected with said last mentioned means, a plurality of separate inductances inductively coupled with said aforementioned inductances, a signal translating circuit, a signal responsive device connected to said circuit and connections between said signal translating circuit and said second mentioned inductances for effectively utilizing the vector sum of the currents in said separate phases.

7. A wired radio communication system comprising in combination a line circuit, means for impressing three phase signaling energy on said line circuit, means for collecting the three phase energy from said line circuit, a plurality of inductances connected with said last mentioned means, a plurality or" separate inductances coupled with said first mentioned inductances, a signal translating circuit connected with said second mentioned inductances, signal observing means actuated by said signal translating circuit and means for reversing the phase relationship of currents in said signal translating circuit whereby the currents in each of said phasesmay be vectorially added for actuating said signal responsive device atan amplitude greater than the amplitude of the current in the separate phases.

8. A wired radio communication system, comprising in combination a line circuit, means for impressing three phase signaling energy on said line circuit, means for collecting the three phase energy from said line circuit, a plurality of inductances connected with said last mentioned means, a plurality of separate inductances inductively coupled with the first mentioned inductances, a signal translating circuit connected with said second mentioned inductances, a signal responsive device connected with said translating circuit, said second mentioned inductances being arranged to shift one of said phases substantially 180 degrees whereby said signal translating device efiectively utilizes the vector sum of said three phase signaling current.

9. A wir'ed radio signaling system, comprising in combination a transmission line circuit, a source of three phase high frequency current, means for connecting said source with said line circuit, receiving apparatus, means for connecting said receiving apparatus with said line circuit, said receiving apparatus comprising a plurality of inductances connected with said second mentioned connecting means, a plurality of separate inductances inductively coupled with said first mentioned inductances, a signal translating and responsive means associated with said separate inductances, said separate inductances being so interconnected and coupled with said first mentioned inductances as to yield a signal response greater t that possible with single phase high frequency transmission and reception under equivalent conditions of transmitting power and receiver sensitivity.

10. A wired radio communication system comprising in combination a three phase electric power transmission line, a source of modulated three phase high frequency current, means for impressing said current on said lines, means for collecting said three phase high frequency current from said lines at a point distant from said source, said collecting means containing three substantially equal inductances, said inductanccs being connected in Y, three additional inductances symmetrically coupled to said first mentioned inductances, said additional inductances being connected in series and in such manner that two are aiding and the third opposing, a translating and signal indicating means associated with said additional inductances, the coupling between said first mentioned and additional inductances being such that the resultant current in said additional inductances is a maximunii and suastantially equal to twice the current which would traverse them under the condition of Zero coupling between any two pairs of said first mentioned and additional inductances and a finite coupling between the third and remaining of said pairs, the individual current values obtained under conditions of said finite coupling being equal to each other.

11. A wired radio receiving system com-- prising in combination a three phase electric power transmission line, three substantially equal inductances connected in Y and with said transmission line, three additional inductances symmetrically coupled to said first mentioned inductances, said additional in ductances being connected in series and in such manner that two are aiding and the third opposing, a translating and signal indicating means associated with said additional inductances, the coupling between said first mentioned and additional inductances being such that the resultant current in said additional inductances is a maximum and substantially equal to twice the current which would traverse them under the condition of zero coupling between any two pairs of said first mentioned and additional inductances and a finite coupling between the third and remaining of said pairs, the

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individual current values obtained under conditions of said finite coupling being equal to each other.

12. A wired radio communication system, cen'iprising in combination athree phase transmission line circuit, a source of three phase high frequency energy means for impressing said energy on said transmission circuit, receiving apparatus, including means for collecting a portion of the three phase high frequency energy from said line circuit, said collecting means being substantially opaque to the passage of low frequency power current from said line circuit, said receiving apparatus containing inductances connected with each phase of said line circuit, a secondary receiving circuit containing secondary inductances inductively associated with two of said first mentioned inductances, a translating and signal indicating means associated With said secondary inductances, said secondary inductances so interconnected and coupled with two of said first mentioned inductanees as to effect a reversal of the phase of the component current induced in the secondary circuit by virtue of the coupling between one inductance of said circuit and one of said first mentioned inductances, from that component induced by virtue of coupling with a second of said first mentioned inductances, in such manner that the vector sum of said component currents is substantially a maximum and is greater than either of said component currents.

13. A wired radio communication system,

comprising in combination a three phase transmission line circuit, a source of three phase high frequency energy, means for impressing said energy on said transmission circuit, receiving apparatus including means for collecting a portion of the three phase high frequency energy from said line circuit, said collecting means being substantially opaque to the passage of 10W frequency power current from said line circuit, said receiving apparatus containing inductances connected with each phase of said line circuit, a secondary receiving circuit containing secondary inductances inductively associated with three or said first mentioned in ductances, a translating and signal indicatin g means associated with. said secondary inductances, said secondary inductances so interconnected and coupled With three of first mentioned inductances as to eilect a reversal of phase of the component current induced in the secondary circuit by virtue of the coupling between one inductance of said circuit and one of said first mentioned inductances from that of the vector sum of the tWo component currents induced by virtue of the coupling between said circuit and two of said first mentioned inductances, in such manner that the resulting vector sum of the said first component current and said vector sum of the said remaining two component currents, is substantially a maximum and is greater than either of said component currents or of the vector sum of two of said component currents.

ROBERT D. DUNCAN, JR. 

